linux-kernel - Re: 2.6.24-rc4-mm1 kobject changes broken with hvcs driver on powerpc

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Date:	Thu, 6 Dec 2007 10:50:06 -0800
From:	Greg KH <greg@...ah.com>
To:	Balbir Singh <balbir@...ux.vnet.ibm.com>
Cc:	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, rsa@...ibm.com, apw@...dowen.org,
	balbir@...ibm.com
Subject: Re: 2.6.24-rc4-mm1 kobject changes broken with hvcs driver on
	powerpc

On Thu, Dec 06, 2007 at 11:49:59PM +0530, Balbir Singh wrote:
> Kamalesh Babulal wrote:
> > Hi Andrew,
> > 
> > The 2.6.24-rc4-mm1 kernel build fails with build failure,
> > 
> >   CC      drivers/char/hvcs.o
> > drivers/char/hvcs.c: In function ‘hvcs_open’:
> > drivers/char/hvcs.c:1180: error: wrong type argument to unary exclamation mark
> > make[2]: *** [drivers/char/hvcs.o] Error 1
> > make[1]: *** [drivers/char] Error 2
> > make: *** [drivers] Error 2
> > 
> > The kref_get begin void return type, check for the kobject return type
> > as in the previous kobject_get()
> > 
> >         if (!kref_get(&hvcsd->kref)) {
> >                 spin_unlock_irqrestore(&hvcsd->lock, flags); 
> >                 printk(KERN_ERR "HVCS: Kobject of open"
> >                         " hvcs doesn't exist.\n");
> >                 return -EFAULT; /* Is this the right return value? */
> >         }
> > 
> > I have tested for the build failure only.
> > 
> > Signed-off-by: Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>
> > --
> > --- linux-2.6.24-rc4/drivers/char/hvcs.c	2007-12-05 12:17:37.000000000 +0530
> > +++ linux-2.6.24-rc4/drivers/char/~hvcs.c	2007-12-05 19:17:12.000000000 +0530
> > @@ -1177,12 +1177,8 @@ fast_open:
> >  	hvcsd = tty->driver_data;
> > 
> >  	spin_lock_irqsave(&hvcsd->lock, flags);
> > -	if (!kref_get(&hvcsd->kref)) {
> > -		spin_unlock_irqrestore(&hvcsd->lock, flags);
> > -		printk(KERN_ERR "HVCS: Kobject of open"
> > -			" hvcs doesn't exist.\n");
> > -		return -EFAULT; /* Is this the right return value? */
> > -	}
> > +	kref_get(&hvcsd->kref);
> > +	spin_unlock_irqrestore(&hvcsd->lock, flags);
> > 
> 
> Why release the spinlock here? It's done after the count is incremented.
> This patch does not seem correct.

Doh, you are correct, I'll make sure that I fix this up before applying
it.

thanks,

greg k-h
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